2012-03-06 paulson 2012-03-06 mathematical symbols instead of ASCII
2009-10-17 wenzelm 2009-10-17 eliminated hard tabulators, guessing at each author's individual tab-width; tuned headers;
2008-02-11 krauss 2008-02-11 Made theory names in ZF disjoint from HOL theory names to allow loading both developments in a single session (but not merge them).
2005-06-17 haftmann 2005-06-17 migrated theory headers to new format
2002-10-01 paulson 2002-10-01 Numerous cosmetic changes, prompted by the new simplifier
2002-07-14 paulson 2002-07-14 improved presentation markup
2002-07-02 paulson 2002-07-02 Tidying and introduction of various new theorems
2002-05-10 paulson 2002-05-10 converted the AC branch to Isar
1994-08-12 lcp 1994-08-12 installation of new inductive/datatype sections
1994-07-27 lcp 1994-07-27 Addition of infinite branching datatypes